No one has mentioned salt except for almonds before.
I just did an almost-a-century (150K) and the thing that really picked me up at 105 k was two cups of broth. Don't know why.
Good thing to bring up. I tried Endurolytes (the capsules) but I found that I just prefer eating/drinking what I need rather than taking pills. I am unsure if this is part of the equation but will think about this as well.